Inkjet printing is one of the most versatile and affordable printing methods available. Since its inception, inkjet technology has improved and proliferated to the point that it can be used in applications ranging from printing simple text documents to printing vivid, complex graphic designs on many types and sizes of paper, film, fabric and other media.
The inks used in inkjet printers can be either dye-based or pigment-based. Each type of ink offers distinct advantages. Dye-based inks use a liquid colorant that is often water-based. The dye tends to be absorbed into the surface of the printed medium, and turns the medium the color of the dye. Dye-based inks are typically more chromatic and provide more highly saturated colors than pigmented inks. Because of their composition, however, water-soluble dye-based inks are usually not water-resistant. They also tend to be more affected by UV light, making them vulnerable to fading or color change over time.
In contrast, pigmented inks use a solid colorant to achieve color. With pigmented inks, colorant particles remain on the surface of the print medium. Once the liquid in the ink has evaporated, the colorant particles will generally not go back into solution, and the resulting color is therefore more water-resistant. In many cases, the line quality and accuracy of plots produced by pigment-based inks are superior to those produced by dye-based inks. In addition, pigmented inks are more UV-resistant than dye-based inks, so that it typically takes longer for noticeable fading of pigment-printed media to occur.
For many types of substrates, such as paper or fabric, either type of ink will readily adhere to or be absorbed into the substrate surface. For polymeric substrates, however, such as plastic films or other plastic products, it is difficult to achieve desired image quality and durability, as polymeric surfaces tend to be resistant to dyes and other colorants. Many polymeric surfaces are resistant to the inks themselves and are difficult to dye because they lack dye sites to which dye molecules can attach. In addition, pigments that are applied to such polymeric surfaces tend to be vulnerable to erosion and/or damage due to wear.
For these reasons, it is desired to provide an inkjet ink that is suitable for use on nonporous plastic or polymeric substrates and provides a durable, high quality image on such substrates without the use of a surface treatment or an ink reception layer.